Jin, M;
(2015)
Low-dimensional Composites for Enhanced Magnetic Resonance Imaging.
Doctoral thesis , (UCL)University College London.
Abstract
The work reported in this thesis aimed to develop new low-dimensional Gd- and Mn-loaded systems for use as magnetic resonance imaging agents. First, core-shell polymer fibers were prepared using electrospinning. Gd(DTPA) (gadolinium(III) diethylene triamine pentaacetate hydrate) was encapsulated into a polyethylene oxide (PEO) core coated with a Eudragit S100 sheath. Analogous fibers were also prepared loaded with the model drug rhodamine B. The fibers were homogeneous, with distinct core-sheath phases. In vitro release studies showed that no more than 10% of the incorporated dye was released from the fibers in acidic solution (pH 1), but sustained release occurred at pH 7.4. Mucoadhesion studies revealed strong adhesive forces between porcine colon mucosa and PEO from the core. The proton relaxivities of Gd(DTPA) released from the fibers were unchanged from the starting complex. This work was built upon to generate theranostic fibers with both Gd(DTPA) and indomethacin in the core. Very little indomethacin was released from the fibers at pH 1, but sustained release was obtained at pH 7.4. The composite fibers displayed increased proton relaxivities (r1=5.03-10.13 s-1mM-1; r2=8.28-14.96 s-1mM-1) over the original Gd(DTPA) complex. The combination of colon targeted delivery and sustained release makes the core-shell PEO/Eudragit fiber system potentially potent for both diagnosis of and treatment of colonic abnormalities. Second, Gd(III) and Mn(II) complexes were intercalated into hydroxy double salt (HDS) nanoparticles. The complexes in most cases were intercalated between the layers of the HDS, but occasionally were surface adsorbed. Certain of the Gd(III) complex-loaded composites had greater relaxivities than Gd(DTPA), indicating they may be potent for magnetic resonance imaging. The Mn(II) complex-loaded composites had lower relaxivities than the pure complexes. Nevertheless, these intercalates may have use as MRI contrast agents for patients with poor kidney function, because Gd(III)-based contrast agents causes severe renal failure.
| Type: | Thesis (Doctoral) |
|---|---|
| Title: | Low-dimensional Composites for Enhanced Magnetic Resonance Imaging |
| Event: | University College London |
| Language: | English |
| Keywords: | Electrospinning, Hydroxy Double Salts, Magnetic Resonance Imaging, Relaxivity |
| UCL classification: | UCL > Provost and Vice Provost Offices UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Life Sciences > UCL School of Pharmacy |
| URI: | https://discovery.ucl.ac.uk/id/eprint/1470389 |
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